FIG. 1 illustrates a known winch 10 for retaining/tightening a cargo-retaining strap. The winch 10 comprises a steel frame 20 including a base 22 having first and second separate base plates 22a,22b that define locations L1,L2 for sliding receipt of a double-L track that is connected to or formed as a part of a cargo trailer or cargo bed, e.g., as part of a “flat-bed” trailer. First and second parallel legs 24a,24b are welded to the base 22 and cooperate with the base to define the frame 20 with an inverted U-shaped structure. A spool 26 is rotatably supported by and between the legs 24a,24b and comprises a slot 26a in which a cargo-retaining strap S is inserted and then wound around the spool for storage/use. The strap S is payed-out from the spool 26 as needed by counter-clockwise rotation of the spool, and retracted as needed by clockwise rotation of the spool 26. The spool 26 includes a driving head (not shown) that projects outwardly from sidewall 24b and that is engaged by a winch bar or other tool to rotate the spool. A ratchet wheel 28 is welded to the spool 26 and rotates therewith adjacent an outer face of sidewall 24a. A pawl 30 is pivotally secured to the sidewall 24a by a bolt, pin or other fastener 32 and pivots between a first position, as shown, where it engages the ratchet wheel 28 and prevents counter-clockwise rotation of the ratchet wheel 28 and spool 26 but allows clockwise rotation for strap tightening operations, and a second position, where it is disengaged from the ratchet wheel 28 to allow free rotation of the ratchet wheel 28 and spool 26 in either direction. The pawl 30 is normally positioned in its first position, as shown, by force of gravity and/or a biasing spring. The base 22 of the winch 10 can also be configured to mate slidably with a flanged side-rail of a cargo trailer or cargo bed, e.g., of a “flat-bed” trailer.
The winch 10 shown in FIG. 1 has been found to be sub-optimal for a variety of reasons. The frame 20, spool 26, ratchet wheel 28 and pawl 30 are defined from ferrous steel and are susceptible to corrosion and can weigh as much as 9 pounds (lbs.) or more. Furthermore, the frame 20, itself, comprises four separate steel pieces (base plates 22a,22b, sidewalls 24a,24b) that must be arranged properly and then welded together which increases assembly time and cost. Furthermore, the weld zones are susceptible to corrosion and/or failure.
FIG. 2 illustrates another known cargo-strap retaining winch 10′ that is structured similarly and functions identically to the winch 10. Unlike the winch 10, however, the winch 10′ comprises a one-piece frame 20′ defined from a steel plate that is bent into the required inverted U-shaped structure so as to comprise a base 22′ and first and second sidewalls 24a′,24b′. The locations L1′,L2′ for slidably mating with a double-L track of a flat-bed trailer or other cargo hauling structure as described above can be machined after the U-shaped frame 20′ is defined or can be defined in the frame-stock prior to the bending operation. The winch 10′ comprises a spool 26′, ratchet wheel 28′ and pawl 30′ that are identical in structure and function to those described above in connection with FIG. 1. The base 22′ of the winch 10′ can also be configured to mate slidably with a flanged side-rail of a cargo trailer or cargo bed, e.g., of a “flat-bed” trailer.
The winch 10′ represents an advantage over the winch 10 in terms of the simplified one-piece structure of the steel frame 20′ which eliminates all welding operations required to construct the frame 20 of the winch 10. Like the winch 10, however, the frame 20′, spool 26′, ratchet wheel 28′ and pawl 30′ of the winch 10′ are defined from ferrous steel and, as such, are susceptible to corrosion in a manner similar to the winch 10 and are high-weight, especially in light of the fact that a single trailer or other cargo bed will typically carry multiple winches, e.g., ten or more.
Another main disadvantage of the winch 10′, resulting from its one-piece U-shaped frame 20′, is that the base 22′ of the frame has a maximum possible width W1 which is only equal to the width W2 defined inclusively between the parallel sidewalls 24a′,24b′. This maximum possible width or “footprint” of the base 22′ has been found to be deficient for certain applications because the forces exerted on the winch 10′ by the strap S are undesirably concentrated within the maximum width W1 of the base. More particularly, the steel-framed winch 10′ is often mated with an aluminum structure such as a double-L track, a flanged side-rail, or the like of a cargo trailer, and this mismatch in material hardness and elasticity has been found to result in damage to the aluminum structure such as, e.g., bending, gouges, and tearing. The steel winch frame 20′ has a much higher hardness and lower elasticity as compared to the aluminum mounting structure of a flat-bed trailer or the like, and this leads to the noted damage to the aluminum structure. For example, 6061-T6 aluminum alloy has a Brinell hardness number (BHN) of 95, while Brinell hardness numbers for common steels, such as those used to manufacture the conventional winches 10,10′, vary between BHN=133 for A569 steel to BHN=250 for A514 and 100×F steels, and BHN=400 for AR400 steel. Furthermore, aluminum alloys commonly used in trailer and other cargo bed manufacturing such as, e.g., 6061-T6 extrusions, have a modulus of elasticity that only ⅓ of the modulus of elasticity of steel, i.e., the deflection of an aluminum structure will be three-times that of a similar steel structure. As such, it can be seen that use of steel winch structures 10,10′ on an aluminum trailer or cargo bed leads to an inherent mismatch in hardness and elasticity, with the common result being that the steel winch permanently damages the aluminum structure. Given the increasing popularity of flat-bed trailers and cargo beds defined entirely from aluminum or having aluminum siderails and/or winch tracks for mating with winches, a need has been identified for a new and improved winch compatible with these aluminum structures.
A further problem associated with use of steel winches 10,10′ on an aluminum alloy trailer or cargo bed is the resulting galvanic or “electrolysis” reaction that occurs between these dissimilar materials in the presence of an electrolyte, e.g., when wet by humidity or rain water. This reaction often causes the winches to become stuck on the winch track in a manner that prevents them from being easily moved to the required location to adjust the position of the cargo straps. Also, the electrolysis reaction speeds corrosion at the interface of the dissimilar metals due to ion exchange and can lead to severe pitting and failure.
New ice and snow control techniques have exacerbated the corrosion of conventional steel winches and also appear to act as a catalyst to the damaging electrolysis reaction between steel winches and aluminum alloy trailers and cargo beds. These new ice and snow control techniques include use of liquid compounds comprising magnesium chloride or calcium chloride that are many times more corrosive to steel as compared to “road salt” as we know it, e.g., sodium chloride. These new techniques are becoming more popular due to a cost advantage and are causing extensive damage to steel components of truck trailers. This phenomenon is documented in the article “Corrosion Explosion” appearing in the September 2004 issue of Trailer/Body Builders, pps. 38-45. As such, it is clear that corrosion of conventional steel winches 10,10′ exposed to these increasingly popular ice/snow control compounds will accelerate and render same unusable and/or unsafe.
Another main disadvantage associated with known winches 10,10′ is that the connection between the pawl 30,30′ and the sidewall 24a,24a′ frame by a bolt or other fastener 32 connected to the frame 20,20′ can be insufficient to hold the high-loads imposed on pawl 30,30′ through the ratchet wheel 28,28′. In particular, the fastener 32 is subjected to high bending and shearing forces that have been found to cause failure of the fastener with the result being an unconstrained ratchet wheel 28,28′ and strap S which can lead to loss of the cargo load. As such, improvements have been deemed desirable in connection with the connection of the pawl 30,30′ to the frame 20,20′ to improve safety.
With reference to FIGS. 2A,2B,2C, the steel frames 20,20′ of the winches 10,10′ lead to another safety deficiency in that the winches 10,10′ are often slidably receivable onto extruded aluminum winch tracks T1,T2,T3 such as double-L tracks defined from aluminum extrusions with a loose or uneven fit that results in gaps G1,G1,G3 between the track and the base 22,22′ of the winch frame. These gaps have been found to be highly undesirable in that forces exerted on the winch are not evenly distributed to the track and are thus more likely to damage the track, especially in light of the material mismatch issues noted above. In order for the winches 10,10′ to fit a double-L track with a more intimate fit, plates and other structures would have to be welded to the frames where needed, or added-thickness plates would need to be used to weld the frame or in the bended frame, and/or other time-consuming processing would be required, and this has not been done owing to economic constraints and/or because others have not recognized this problem of using steel winches on aluminum winch tracks.